While it does not answer your question, I just want to mention that the widebody board is just a motherboard which hosts a standard V5 nano decoder on it. Speaker traces go directly from the solder pads to the E24 connector.
The problem is likely with the nano decoder plugged into the widebody board. If you have another nano with a wire interface, you could unplug the nano from the widebody board and snap on the wire adapter, then see if the problem remains.
Either way, these are sold as a set of the widebody adapter and the nano piggybacked onto it. If it is defective, you will likely have to return the complete set.